Digger chain



Nov. 8, 1932. Q U P 11,886,382

DIGGER CHAIN Original Filed May 31, 1930 INVENTOR Lo Ga '3" BY Q .9

\ ATTORNEY Patented Nov. 8, 1232 UNITED STATES LESTER G. DUNLAP, OF STOCKTON, CALIFORNIA BIGGER CHAIN Application filed May 31, 1930, Serial This invention relates to endless digger chains such as are used on ditch digging machines, being mounted about sprocket wheels, one of which is carried on the end of a boom which depends into the ditch as it is dug. Such a chain for instance is shown in my Patent No. 1,397,679, granted November 22, 1921. This previous digging chain was very eflicient in ordinary ground but did not prove to be very successful in hard ground owing to the fact that the ground over the entire width of the ditch was engaged simultaneously by a single blade, which obviously placed a very heavy strain on said blade when work- 5 ing in ground of this character.

The principal object of the present invention is to provide a digging chain of the general character above outlined in which the digging elements are so disposed that the cut will not be taken for the full width of the ditch at any point or from a single link of the chain, but is disposed along a number of links. The digging strains on the individual links of the chain are therefore lessened over what is the case with the device of the above mentioned patent or of the ordinary digging structure, and will consequently operate more successfully in hard ground. Also .on account of this novel arrangement of the digging elements the heavy vibrations on the chain which accompany the functioning of said other usual forms, are reduced to a considerable extent.

A further object of the invention is to arrange the cutting elements at their digging or cutting edges so that they will remain in a sharp condition without attention for a considerable length of time.

A further object of the invention is to produce a simple and inexpensive device and yet one which will be exceedingly efl'Tective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Fig. 1 is a fragmentary side elevation of No. 457,921. Renewed April 18, 1982.

my improved digging chain showing a complete digging unit or assembly.

Fig. 2 is a top plan outline of the chain links of the digging assembly, showing the relative positions of the digging blades of such assembly.

Fig. 3 is an end view of one of the cutting elements, to dig the side portions of a ditch. Fig. 4 is a similar view of another cutting element, to dig a part of the intermediate portion of the ditch.

.Referring now more particularly to the characters of reference on the drawing, three chain links, themselves of any standard form to engage standard sprocket wheels, are necessary to provide a complete digging unit, or so as to engage and traverse the dirt over the entire width of the ditch being dug. One of these links 1 has rigid arms 2 depending from the side bars of the link in converging relation to each other to form a V, as shown in Fig. 4. From the apex of these arms a single arm 3 depends, which is disposed substantially central of the width of the link. At its lower end this arm is formed with a right angle lateral member 4 projecting to one side only of said center of width of the link and forming a cutting blade. This blade, along its forward edge, and the adjacent edge of the arm 3, are inwardly beveled as at 5 to form cutting edges. Said blade and arm on the outside and .in the planes of the beveled orsharpened portions are backed by an extra hard layer of a special metal, as indicated at 6,which is welded 35 or otherwise suitably united to the metal of the arm and blade. This feature insures that the beveled surface of the blade, which is relatively soft, 'will wear down first and the blade will therefore retain its beveled and consequently sharp form indefinitely. The blade slopes upwardly from its cutting edge toward the rear so that said edge only engages the dirt and with a chisel-like action.

Another link 7 also has a lateral cutting blade 8 projecting from a supporting arm structure 9, the same as the arms 2 and 3.

In this case however the blade projects laterally in a direction op osite to the blade 4, as shown in Fig. 2. till another link 10 mo of the chain carries lateral and oppositely extending arms 11, from the outer ends of which vertical arms 12 depend, the spacin between which arms determines the widt of the ditch. These arms are disposed in slightly converging relationship to each other toward their rear ends, or in the direction opposite to that in which the chain is adapted to travel, in order to have a draft 0 or clearance with the sides of the ditch.

These arms at their lower ends carry laterally extending cutting blades 13 which face each other. The inner side edges of these blades are disposed in the longitudinal planes 15 of the outer side edges of the blades 4 and 8;

while the inner or adjacent edges of the latter blades lie substantially in common longitudinal alinement with each other. From the more or less diagrammatic showing of 2 Fig. 2, it will therefore be seen that the blades 13 dig only the outermost or side portions of the ditch, while the blades 4 and 8 dig the intermediate portions; and the combined digging action of all the blades together forms the complete ditch, without an overlaps or without any dirt being misse It will also be seen that owing to the distribution of the cutting action over a number of links, the strain on any one link is rela- 9 tively light and consequently the vibration of the chain as it digs is minimized. Also due to the fact that each blade only makes a relatively small cut the chain operates successfully in hard ground at a. greater speed, and with a lesser expenditure of power, than the ordinary chain is capable of and in which each blade makes a full-width cut. The particular arrangement of the blade supporting arms substantially centralizes the strains on ;the links, so that there is little tendency to side drag or twist, even though the blades themselves are of course offset from the central plane of the links.

Though I have only specifically described the construction and particular arrangement of the blade 4 and its arm, it is to be understood that all the blades and the adjacent portions of their arms are bevel-sharpened, and are backed by thehard metal layer 6. Also all the blades are set with an upward slope from their cutting-edges to the rear, so that they will all engage the ground with the same chisel action. This upward slope also provides dirt engaging surfaces for the dirt after it is dug, which, with the high speed of travel of the chain, is suificient to cause such dirt to be thrown clear of the ditch.

Though I have here shown the various C9 I cutting blades as being mounted on adjacent links, plain links may be interposed therebetweenif desired in order to increase the spacing of the blades. Also it is not necessary that the various blades have the identical 'positions relative to each other as shown, as

long as the three links and their blade units are associated with each other in some manner to form the complete cutting unit.

From the fore oing description it will be readily seen that haveproduced such a device as substantially fulfills the objects of the invention as set forth herein.

While this specification sets forth in detall the present and preferred construction of the devlce, still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the inventlon, as defined by the appended claims.

Having thus described my invention what I cla m as new and useful and desire to secure as by Letters Patent is: 1. In a digger chain, a digger unit consistmg of laterally extending and longitudinally separated blades projecting in opposite directions from the transverse center of the chain, other laterally extending blades longitudinally spaced from said first named blades to engage the ground from and outwardly of the longitudinal planes of the outer edges of said first named blades, and rigid connectmg means between the individual blades and correspondingly spaced links of the chain.

2. In a digger chain, a digger unit consisting of laterally extending and longitudinally separated blades projecting in opposite directions from the transverse center of the chain, other laterally extending blades longitudinally spaced from said first named blades to engage the ground from and outwardly of the longitudinal planes of the outer edges of said first named blades, arms depending from separate links of the chain and connected to the first named blades along their inner edges, and arms secured to another link of the chain and connected to the last 105 named blades along their outer edges.

3. A structure as in claim 2, in which the forward edges of the arms are sharpened adj acent their connection with the corresponding blades.

4. A digger chain comprising links, a digging unit depending therefrom, said unit including longitudinally spaced blades projecting laterally in opposite directions from the center of width of the chain, and arms up- 115 standing from and rigid with the blades at their inner ends; the upper ends of said arms being formed with transversely diverging branches connected to the transversely spaced side elements of the corresponding links.

In testimony whereof I afiix my signature.

LESTER G. DUNLAP. 

